Abstract: The present invention provides a support beam for use in an easily polymerizeable substance treatment apparatus. The support beam supports or reinforces an internal provided in the easily polymerizeable substance treatment apparatus. The support beam has an internal mounting portion to which the internal is attached, and a folded-back portion, at least part of which, is inclined downward with respect to a horizontal direction when approaching an end thereof.

Abstract: A catalytic combustion apparatus is equipped with a reactor for catalytically burning a gas to be treated containing a combustible organic compound, which further comprises a condensate forming means for condensing a part of a gas after reaction in the reactor, to form a condensate, and a pH measuring means for measuring a pH of the resultant condensate. It is preferred that the catalytic combustion apparatus still further comprise a temperature adjusting means for adjusting a temperature of at least a catalyst-packed portion of the reactor based on data measured by the pH measuring means.

Abstract: The method for preserving a catalyst of the present invention is characterized in that, in a process for continuously producing an objective product by a vapor phase oxidation reaction using a phosphorus-molybdenum-vanadium catalyst containing phosphorus, molybdenum and vanadium, the phosphorus-molybdenum-vanadium catalyst retained in a reactor is maintained under a condition of a water content of 30 mg or less per 1 g of catalyst dry weight, before the start of the reaction or during the stop of the reaction. By this, deterioration of the catalyst retained in the reactor can be simply prevented.

Abstract: The present invention provides a support beam for use in an easily polymerizeable substance treatment apparatus for treating easily polymerizeable substances, the support beam being for supporting or reinforcing an internal provided in the easily polymerizeable substance treatment apparatus; comprising an internal mounting portion to which the internal is attached, and a folded-back portion at which the internal mounting portion is folded back so that at least part of the folded-back portion is inclined downward when approaching an end thereof.

Abstract: The method for preserving a catalyst of the present invention is characterized in that, in a process for continuously producing an objective product by a vapor phase oxidation reaction using a phosphorus-molybdenum-vanadium catalyst containing phosphorus, molybdenum and vanadium, the phosphorus-molybdenum-vanadium catalyst retained in a reactor is maintained under a condition of a water content of 30 mg or less per 1 g of catalyst dry weight, before the start of the reaction or during the stop of the reaction. By this, deterioration of the catalyst retained in the reactor can be simply prevented.

Abstract: A catalytic combustion apparatus is equipped with a reactor for catalytically burning a gas to be treated containing a combustible organic compound, which further comprises a condensate forming means for condensing a part of a gas after reaction in the reactor, to form a condensate, and a pH measuring means for measuring a pH of the resultant condensate. It is preferred that the catalytic combustion apparatus still further comprise a temperature adjusting means for adjusting a temperature of at least a catalyst-packed portion of the reactor based on data measured by the pH measuring means.

Abstract: A molybdenum-based precipitate is prepared according to a process including the first step of forming a crude precipitate by pH adjustment to 6.5 or less in the presence of an alkali metal compound, and the second step of dissolving the crude precipitate in aqueous ammonia and forming a precipitate by pH adjustment to 6.5 or less. Then, the resulting molybdenum-based precipitate is washed with an acid aqueous solution having a pH of 6.5 or less and containing not less than 0.01 mole/L of ammonium root. Thus, a change in average particle diameter can be suppressed and good workability can be achieved, so that a molybdenum-based precipitate having a high purity and a desired average particle diameter can be obtained.

Abstract: The present invention relates to the effective utilization of a used catalyst containing at least molybdenum, an A element (at least one element selected from the group consisting of phosphorus and arsenic) and an X element (at least one element selected from the group consisting of potassium, rubidium and cesium), and provides a process for producing a catalyst, which comprises dispersing said used catalyst in water, adding thereto an alkali metal compound and/or ammonia solution, adjusting the resulting mixture to pH 6.5 or less to generate a precipitate containing at least molybdenum and the A element, and using the precipitate as a material for catalyst-constituting elements.

Abstract: A process for producing methyl methacrylate, which comprises subjecting methacrolein and methanol to direct esterification reaction to thereby obtain a reaction mixture liquid containing at least methyl methacrylate and methanol, adding additional methacrolein to the reaction mixture liquid as an entrainer, and distilling the resulting reaction mixture liquid to recover the methanol.

Abstract: A molybdenum-based precipitate is prepared according to a process including the first step of forming a crude precipitate by pH adjustment to 6.5 or less in the presence of an alkali metal compound, and the second step of dissolving the crude precipitate in aqueous ammonia and forming a precipitate by pH adjustment to 6.5 or less. Then, the resulting molybdenum-based precipitate is washed with an acid aqueous solution having a pH of 6.5 or less and containing not less than 0.01 mole/L of ammonium root. Thus, a change in average particle diameter can be suppressed and good workability can be achieved, so that a molybdenum-based precipitate having a high purity and a desired average particle diameter can be obtained.